<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>LocalStorage</title>
  <link rel="stylesheet" href="style.css">
</head>

<body>
  <!--
      Fish SVG Cred:
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  <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 512 512"
    enable-background="new 0 0 512 512" xml:space="preserve">
    <g>
      <path d="M495.9,425.3H16.1c-5.2,0-10.1,2.9-12.5,7.6c-2.4,4.7-2.1,10.3,0.9,14.6l39,56.4c2.6,3.8,7,6.1,11.6,6.1h401.7   c4.6,0,9-2.3,11.6-6.1l39-56.4c3-4.3,3.3-9.9,0.9-14.6C506,428.2,501.1,425.3,495.9,425.3z M449.4,481.8H62.6L43,453.6H469   L449.4,481.8z"
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      <circle cx="398.8" cy="273.8" r="14.1" />
    </g>
  </svg>

  <div class="wrapper">
    <h2>LOCAL TAPAS</h2>
    <p></p>
    <ul class="plates">
      <li>Loading Tapas...</li>
    </ul>
    <form class="add-items">
      <input type="text" name="item" placeholder="Item Name" required>
      <input type="submit" value="+ Add Item">
    </form>
  </div>

  <script>
    //在关闭浏览器之后清除缓存
    // window.onbeforeunload = function (e) {
    //   localStorage.removeItem('items');
    //   // let confirmationMessage = "\o/";
    //   e.returnValue = confirmationMessage; // Gecko, Trident, Chrome 34+
    //   // return confirmationMessage; // 如果有返回值的话，就会弹出确认框。
    // };
    // window.onbeforeunload = function (event) {
    //   var message = 'Important: Please click on \'Save\' button to leave this page.';
    //   if (typeof event == 'undefined') {
    //     event = window.event;
    //   }
    //   if (event) {
    //     event.returnValue = message;
    //   }
    //   return message;
    // };
    const addItems = document.querySelector('.add-items');
    const itemsList = document.querySelector('.plates');
    const items = JSON.parse(localStorage.getItem('items')) || [];

    function addItem(e) {
      e.preventDefault();
      const text = this.querySelector('[name=item]').value;
      const item = {
        text, // ES6的简写形式 => text = text;
        done: false
      };
      items.push(item);
      localStorage.setItem('items', JSON.stringify(items));
      populateList(items, itemsList);
      this.reset(); // 添加完数据后，重置输入框      
    }

    function populateList(populates = [], place) { // 设置默认值，防止传参数出错的时候crash
      place.innerHTML = populates.map((populate, index) => {
        return `
          <li>
            <input type="checkbox" id=item${index} data-index=${index} ${populate.done ? 'checked' : ''}>
            <label for="item${index}">${(populate.text)}</label>
          </li>
        `; //之所以用‘’空字符是因为如果用null的话，会出现在html中
      }).join(''); // join()之后一定要加''，表示空字符，否则会加入逗号，造成错误  
    }

    function toggleDone(e) {
      // if(!e.target.nodeName.match('INPUT')) return;
      if (!e.target.matches('input')) return; // 跳过所有的input，只处理label
      const node = e.target;
      const index = node.dataset.index;
      items[index].done = !items[index].done;
      localStorage.setItem('items', JSON.stringify(items));
      populateList(items, itemsList);
    }

    addItems.addEventListener('submit', addItem);
    itemsList.addEventListener('click', toggleDone);

    populateList(items, itemsList);

    // 3 addtion function
    // Check all
    // Uncheck all
    // Clear all
  </script>


</body>

</html>